There are circumstances where Arel is the only way to write a given scope or predicate composably.
Competent developers use it, and write tests for their Arel expressions because they know it’s an API that may have breaking changes across minor releases.
Unfortunately, issue reports involving Arel in application code are met with a bureaucratic and patronising “it’s an internal/private API”. I’m always left wondering, “private/internal to who?” Disappearing the Arel documentation was a further dismaying barrier to contribution.
It’s not just a WTF. These incidents are a FU, every time.